CF3B5 reverse fan

README.md

@@ -12,6 +12,8 @@ Features merged into the master branch:
 
 - [fan: Normalising Fan PWM power](https://github.com/DangerKlippers/danger-klipper/pull/44) ([klipper#6307](https://github.com/Klipper3d/klipper/pull/6307))
 
+- [fan: Reverse FAN](https://github.com/DangerKlippers/danger-klipper/pull/51) ([klipper#4983](https://github.com/Klipper3d/klipper/pull/4983))
+
 - [heater: Modify PID without reload](https://github.com/DangerKlippers/danger-klipper/pull/35)
 
 - [heater: Velocity PID](https://github.com/DangerKlippers/danger-klipper/pull/47) ([klipper#6272](https://github.com/Klipper3d/klipper/pull/6272))
@@ -22,6 +24,7 @@ Features merged into the master branch:
 
 - [probe: Drop the first result](https://github.com/DangerKlippers/danger-klipper/pull/2) ([klipper#3397](https://github.com/Klipper3d/klipper/issues/3397))
 
+
 "Dangerous Klipper for dangerous users"
 
 [![Klipper](docs/img/klipper-logo-small.png)](https://DangerKlippers.github.io/danger-klipper/)

docs/Config_Reference.md

@@ -2892,6 +2892,11 @@ information.
 #gcode_id:
 #   If set, the temperature will be reported in M105 queries using the
 #   given id. The default is to not report the temperature via M105.
+#reverse: False
+#   If true, the working mode of the fan is reversed. If the temperature
+#   is lower than the target temperature, the fan speed increases;
+#   otherwise, the fan speed decreases.
+#   The default is False.
 ```
 
 ### [fan_generic]

klippy/extras/temperature_fan.py

@@ -139,15 +139,22 @@ def set_max_speed(self, speed):
 class ControlBangBang:
     def __init__(self, temperature_fan, config):
         self.temperature_fan = temperature_fan
+        self.reverse = config.getboolean("reverse", False)
         self.max_delta = config.getfloat("max_delta", 2.0, above=0.0)
         self.heating = False
 
     def temperature_callback(self, read_time, temp):
         current_temp, target_temp = self.temperature_fan.get_temp(read_time)
-        if self.heating and temp >= target_temp + self.max_delta:
-            self.heating = False
-        elif not self.heating and temp <= target_temp - self.max_delta:
-            self.heating = True
+        if (
+            self.heating != self.reverse
+            and temp >= target_temp + self.max_delta
+        ):
+            self.heating = self.reverse
+        elif (
+            not self.heating == self.reverse
+            and temp <= target_temp - self.max_delta
+        ):
+            self.heating = not self.reverse
         if self.heating:
             self.temperature_fan.set_speed(read_time, 0.0)
         else:
@@ -167,13 +174,15 @@ def temperature_callback(self, read_time, temp):
 class ControlPID:
     def __init__(self, temperature_fan, config):
         self.temperature_fan = temperature_fan
+        self.reverse = config.getboolean("reverse", False)
         self.Kp = config.getfloat("pid_Kp") / PID_PARAM_BASE
         self.Ki = config.getfloat("pid_Ki") / PID_PARAM_BASE
         self.Kd = config.getfloat("pid_Kd") / PID_PARAM_BASE
         self.min_deriv_time = config.getfloat("pid_deriv_time", 2.0, above=0.0)
-        self.temp_integ_max = 0.0
-        if self.Ki:
-            self.temp_integ_max = self.temperature_fan.get_max_speed() / self.Ki
+        imax = config.getfloat(
+            "pid_integral_max", self.temperature_fan.get_max_speed(), minval=0.0
+        )
+        self.temp_integ_max = imax / self.Ki
         self.prev_temp = AMBIENT_TEMP
         self.prev_temp_time = 0.0
         self.prev_temp_deriv = 0.0
@@ -198,13 +207,18 @@ def temperature_callback(self, read_time, temp):
         # Calculate output
         co = self.Kp * temp_err + self.Ki * temp_integ - self.Kd * temp_deriv
         bounded_co = max(0.0, min(self.temperature_fan.get_max_speed(), co))
-        self.temperature_fan.set_speed(
-            read_time,
-            max(
-                self.temperature_fan.get_min_speed(),
-                self.temperature_fan.get_max_speed() - bounded_co,
-            ),
-        )
+        if not self.reverse:
+            self.temperature_fan.set_speed(
+                read_time,
+                max(
+                    self.temperature_fan.get_min_speed(),
+                    self.temperature_fan.get_max_speed() - bounded_co,
+                ),
+            )
+        else:
+            self.temperature_fan.set_speed(
+                read_time, max(self.temperature_fan.get_min_speed(), bounded_co)
+            )
         # Store state for next measurement
         self.prev_temp = temp
         self.prev_temp_time = read_time